In a cellular mobile communication system, suppression of interference between base stations is required for the achievement of higher transmission capacity. As a conventional technique to reduce interference between base stations, there is known a method for suppressing transmission of radio waves in an unwanted direction using antenna directivities (see, for example, Patent literature 1).
FIG. 1 illustrates the configuration of a wireless communication apparatus that is intended to suppress interference between base stations using antenna directivities. The number of mobile stations is herein assumed to be two.
As shown in FIG. 1, wireless communication apparatus 3 comprises antennas 11, 12, switches 13,14, signal separating unit 15, signal recovering units 16,17, transmission signal generating units 21, 22, directivity determining unit 31, resource assigning unit 32, and signal multiplexing unit 33.
At the signal reception, switches 13 and 14 capture within wireless communication apparatus 3 respective reception signals SRX1, SRX2 that were received by antennas 11, 12, respectively. Directivity determining unit 31 receives as input reception signals SRX1, SRX2, determines reception antenna directivity for each mobile station (not shown), and outputs antenna directivity signals SDC1 and SDC2. Using antenna directivity signals SDC1 and SDC2 indicative of the antenna directivity for each mobile station, signal separating unit 15 separates reception signals SRX1, SRX2 into signal components that were transmitted from respective mobile stations, and outputs reception mobile station signals SRXMS1, SRXMS2. Signal recovering units 16, 17 receive as input respective reception mobile station signals SRXMS1, SRXMS2, recover transmission information from each mobile station, and output respective recovered mobile station signals SRSMS1, SRSMS2. Resource assigning unit 32 receives as input service quality signal SQOS, assigns resources of transmission signals to each mobile station, and outputs resource assignment signal SRA1, SRA2. Transmission signal generating units 21, 22 receive as input respective transmission information STXI1, STXI2, respective antenna directivity signals SDC1 and SDC2 and respective resource assignment signals SRA1, SRA2, and output transmission signals STXS1-1 and STXS1-2, STXS2-1 and STXS2-2, respectively. Signal multiplexing unit 33 receives as input transmission signals STXS1-1, STXS1-2, STXS2-1, STXS2-2, multiples the transmission signals, and outputs multiplexed transmission signals SDTXS1, SDTXS2.
By thus using antenna directivity control in the transmission of signals to each mobile station for each base station (wireless communication apparatus 3), it is possible to reduce interference between base stations A1 and A2, as illustrated in FIG. 2. In FIG. 2, there exist high-speed mobile station M1-1 and low-speed mobile station M2-1 within the cell of base station A1, and there exist high-speed mobile station M1-2 and low-speed mobile station M2-2 within the cell of base station A2.    Patent literature 1: JP2003-198508A